My advice on these types of situations is pretty much always the same. Only a few important factors. Most of the rest is just marketing crap.
1. What do your friends shoot with? If you have any friends who shoot with a DSLR, go with what they shoot with. They can offer support, let you borrow gear, and you can learn together.
2. What feels better in your hand? The ergonomics are all different. Each manufacturer puts things in different places. For me, a Canon just feels backwards and my hands rebel against holding a Sony. Nikon just fits me. Everything is where I want it, and it just works for me. Canon shooters feel the same about their cameras. Sony users just don't know any better, but it's not their fault.
3. What do your local shops support? Swing by your local camera store, figure out what batteries, chargers, lenses, flashes, etc they keep in stock. A couple of times, I've been saved on a shoot for the next day because my local store had something in stock I needed. Like, absolutely needed. One time my charger died on me. Couldn't charge my camera battery. If I had to order it online, I would have missed a shoot. Instead, I swung by the shop, picked one up, and everything worked out fine. Local support is important.(which brings me back to my first point, if your friends can offer a support network, it can be invaluable).
As far as which one is 'best'...well, I would say the Nikon D3s is probably the best camera on the market with regards to the big manufacturers, but you aren't going to be buying the flagship model. You are going to be buying a entry to mid-level consumer camera. At that level, it just doesn't matter. They are all about the same.
Really, the decision should be based on the 3 items I mentioned above. The specs at that level just aren't different enough to matter.